Sort list on Access Group

The situation is that I have a lot of members of a club divided by geographical areas.
The areas are the access groups in joomla so a member in kent and a manager in kent cannot post an article in the category for Essex and the Essex manager cannot post in the category for Kent as their access levels do not allow it.

I would like to show a members list using CB lists. That part if fine. But I need to sort them by the area which is not a field in CB but the access group.

Is there a way to either sort by access level so you can see all the kent members together, all the essex members grouped together but all in the same list.. Or perhaps a way to make a field synchronise with the access group so that the field could be the sort and if a member was moved from Kent to Essex that would update in their profile.

Thank you kindly for your responses

You can sort by whatever you want using the Advanced mode for sorting as it directly lets you extend the ORDER BY part of the userlist query. For that query the alias for _comprofiler table is "ue", alias for _users table is "u", and alias for _user_usergroup_map is "g". So the usergroup mapping has already been joined to the table.